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Manganese (Mn) has been identified as a regulatory bottleneck in carbon (C) turnover because of its role as an enzymatic co-factor in the oxidative decomposition of C by Mn-peroxidase (MnP). We tested this limit on decay using forest soils from coastal British Columbia with contrasting Mn concentrations. Moderately weathered soils (Brunisols) had an average 3.6-fold increase in MnP activity within the upper soil profile in comparison to highly weathered Podzols. Ordination of the Agaricomycete fungal community, which are responsible for MnP production, confirmed significant differences in assemblages between soil types for saprotrophic fungi, particularly species within Agaricales, Trechisporales and Auriculariales. Ectomycorrhizal fungi of Pseudotsuga menziesii were equally aligned with soil type and select taxa more abundant on Brunisols may have supplemented MnP activity. A laboratory incubation with an Mn amendment produced significant interactions in MnP activity by soil type. Surprisingly, MnP activity of both Brunisol substrates declined substantially with an amendment (-56% and − 40% for forest floor and mineral soil, respectively), in contrast to Podzols (-30% and + 26%, respectively). This inhibitory response was linked to considerable uptake of the added Mn in Brunisols, and underscores how Mn2+ likely operates directly on fungi as a regulator of mnp transcription for MnP production. Our study highlights a new perspective concerning the abiotic drivers underpinning the expansive soil C stocks across perhumid temperate rainforests of the Pacific Northwest.

Aims The morphological traits of fine roots change with forest succession and soil weathering. However, low tree species diversity in boreal forests may limit plastic responses of the roots to soil nutrient loss. We tested whether pine trees (Pinus sylvestris L.) have root plasticity to change fine root allocation to deeper soil horizons in response to varying degree of podzolization. Methods We compared root biomass in two sand dune chronosequences (aluminium (Al)/iron (Fe) oxide-poor coarse-textured sand vs. oxide-rich fine-textured sand) in Estonia. Results We found that faster podzolization in coarse-textured soil promotes migration of Al/Fe oxides and phosphorus (P) into deeper horizons and reshapes the depth distribution of fine root biomass. A decrease in P availability in the coarse-textured soil profile increases fine root biomass and length in both the organic and mineral horizons. In the fine-textured old soil, fine root distribution increases in the mineral soil (especially, spodic horizon) rich in oxide-bonded P.Conclusion Pine roots have two plasticities in low-diversity boreal forests – changing root morphological traits and changing depth distribution of root biomass, depending on the abundance of Al and Fe oxides and the depth distribution and dominant form of P.

Aims: We investigated morphological variations in podzols caused by changes in soil porosity and permeability upon the growth of large tree-roots in a tropical barrier island (Ilha Comprida, Brazil). Methods: Soil morphology was described in a continuous lateral sequence of podzols on a 35 m-long cliff. A soil thin section was used to characterize organic matter (OM) accumulation and to estimate soil porosity, permeability, and saturated hydraulic conductivity (Ksat). Soil texture and the contents of organic carbon, Al, and Fe were determined for each pedogenic horizon containing large tree-roots. The evolution of podzol morphology was interpreted in the context of age determinations by optically stimulated luminescence and 14C. Results: Taproots of cashew trees (Anacardium occidentale) penetrated the cemented Bhm horizon and the massive-clayey 2Cgj horizon. Aligned with the taproot, we found a vertical OM-band with lower porosity, permeability, and Ksat than the adjacent Bh and E horizons. Irregular or broken boundaries between the E and Bh horizons were caused by large tree-roots. While the maximum age of these podzols is 3390 ± 530 years, significant and rapid changes in the Bh-horizon morphology occurred within the lifetime of the cashew trees (~ 50 years). Conclusions: The interplay between reduction in flow adjacent to large taproots and the enhanced vertical infiltration at depth has resulted into the development of irregular and broken boundaries between the E and Bh horizons. Because tree-roots alter both local soil porosity and water flow paths, they simultaneously cause the formation and degradation of podzol Bh-horizon.

Temperatures of sandy podzols of middle taiga pine forests with moss and lichen ground cover were analyzed which had been exposed to ground fires of low to medium intensity. In general, temperatures in lichen and moss plots of the pine forests under study, are close to each similar, but in the first year after a fire a noticeable contrast was observed. The reasons are an increase in the amplitude of daily temperatures on the soil surface and stronger heating of upper mineral layers. Temperatures in the mineral layer with depths up to 30 cm depend on the thickness of the forest floor. Analysis of the results show that the duration of post-fire effects in pine forests with sandy podzols is determined by a number of factors: the intensity of the fire, the degree of erosion of the ground cover and litter, and the recovery rate of these components.

Several studies related to CH4 cycling focus on the effect of elevated atmospheric CO2 levels on soil methanogenesis and methanotrophy. However, periodically waterlogged soils are characterized by much higher CO2 concentrations, while aggregates forming in arable soils due to traditional cultivation may be a natural CH4 source for low-affinity methanotrophs. We present a comprehensive laboratory investigation into both methanogenesis and methanotrophy in three different soils under ambient and high CO2 concentrations. The tested materials were agricultural soils widely distributed in Europe: Eutric Cambisol, Haplic Podzol and Mollic Gleysol with determined properties: Corg, Ntot, clay, silt, sand, pH, NO3−, NH4+. We conducted two independent experiments on methanogenesis (flooded conditions) and methanotrophy (non-flooded conditions). All samples for both studies were divided into three sets which differed in the initial CO2 concentration in headspace: ambient CO2 (0.03% v/v ± 0.005), and two high CO2 levels (5% ± 0.4 and 10% ± 0.5 v/v CO2). Moreover, 1% (v/v) of CH4 was added to all sets prepared for the methanotrophy test since low-affinity methanotrophy in the tested soils had been reported previously. Gas concentrations (CH4, CO2, O2) in headspace were measured using gas chromatography method. We observed that the examined soils differed in their ability to produce CH4 as follows: Haplic Podzol = Eutric Cambisol > Mollic Gleysol, as well as to consume CH4: Mollic Gleysol > Haplic Podzol > Eutric Cambisol. The CH4 emissions started faster in Gleysol, but the final CH4 concentration and CH4 production rate in this soil were significantly lower than in the two other soils. The CH4 uptake rate significantly differed among the tested soils. The MANOVA confirmed the significance of the soil-type factor in determining both process rates, whereas the effect of CO2 level and the interaction between both factors were not significant. The amount of consumed O2 during CH4 oxidation was also characteristic for examined soil, but did not differ significantly between CO2 variants. CH4 production and consumption in three different soils (Eutric Cambisol, Haplic Podzol and Mollic Gleysol) collected from periodically waterlogged arable fields were more strongly affected by soil properties than by high CO2 concentration. In contrast, the high CO2 level significantly decreased CO2 production accompanying tested the CH4-related processes.

Vegetation emissions of volatile organic compounds (VOCs) are intensively studied world-wide, because oxidation products of VOCs contribute to atmospheric processes. The overall aim of this study was to identify and quantify the VOCs that originate from boreal podzolized forest soil at different depths, in addition to studying the association of VOC concentrations with VOC and CO2 fluxes from the boreal forest floor. This is the first published study that measures belowground VOC concentrations at different depths in a podzol soil combined with simultaneous flux measurements from the boreal forest floor. The VOC concentrations were determined by sampling VOCs from air inside soil layers using the gas collectors and adsorbent tubes. Forest floor VOC fluxes were determined using a dynamic enclosure technique. All the VOC samples were analysed using a thermal desorption-gas chromatograph-mass spectrometer. More than 50 VOCs, dominated by monoterpenes and sesquiterpenes, were detected in the air space in the soil during two measurement campaigns. The O-horizon was a significant monoterpene source, because it contained fresh isoprenoid-rich litter. Belowground monoterpene concentrations were largely decoupled from forest floor monoterpene fluxes; thus, it seems that production processes and storages of VOCs partly differ from those VOCs that are simultaneously released from the forest floor. Both fluxes and concentrations of the monoterpenes and sesquiterpenes correlated with the CO2 fluxes in autumn, indicating that VOC release was driven by microbial activity. This is the first study where below-ground VOC concentrations were quantified in situ, and for this reason, this study provides valuable insights to the VOC sources present in soils.

The spatial variability in soil physical and hydraulic properties for a managed podzol was assessed using soil apparent electrical conductivity (ECa). Two EMI sensors, the multi-coil (MC) and multi-frequency (MF), were adopted for measurement of ECa on a silage- corn experimental plot in western Newfoundland, Canada. Results demonstrated a significant relationship between the ECa mean relative differences (MRD) and the soil moisture content MRD (R2 = 0.33 to 0.70) for both MC and MF sensors. The difference in depth sensitivity between MC and MF sensors accounted for the variation (0.015 to 0.09) in ECa standard deviation of the relative differences. A significant linear relationship was found between the ECa MRD and sand (R2 = 0.35 and 0.53) or silt (R2 = 0.43), but not with clay (R2 = 0.06 and 0.16). The spatial variability of the ECa-based predictions (CV = 3.26 to 27.61) of soil properties was lower than the measured values (CV = 5.56 to 41.77). These results inferred that the temporal stability of ECa might be a suitable proxy to understand the spatial variability of soil physical and hydraulic properties in agricultural podzols.

Acidic forest soils with two dominant understories, bilberry (Vaccinium myrtillus L.) or alpine lady fern (Athyrium distentifolium Tausch ex Opiz), have been investigated to evaluate the influence of the understory on sorption properties and aluminium behaviour. We investigated acidity, cation exchange properties, organic matter content (SOM) and quality as well as Al bonding to organic matter in humus horizons of soils taken from two different locations. SOM was the major contributor to total cation exchange capacity (CECt) and effective cation exchange capacity (CECe), and a strong relationship was found between SOM and both CECt and CECe, independently of the understory and location. SOM differed in quality, having more fulvic acids in soils under bilberry than in soils under alpine lady fern. For that reason, SOM in soils under bilberry complexed more Al in the exchangeable form in the soluble fulvic acid fraction such that they could be easily washed out, while in soils under alpine lady fern aluminium was mainly bound more stably. We also found that the chemical character of Al depended on the understory type. In soils under bilberry the relation between base saturation and pH could be successfully modelled by a modified Henderson–Hasselbalch equation when Al was considered as a base cation, which is typical for forest podzols. However, in soils under alpine lady fern, this model was efficient only when Al was treated as an acid cation. We concluded that alpine lady fern as the main understory species reduces solubility and potential toxicity of aluminium, thus significantly affecting soil biogeochemistry.

The dynamics of forests dominated by European beech (Fagus sylvatica) and Norway spruce (Picea abies) have been studied intensively. However, mainly due to a lack of long-term data, little is known about how these dynamics interact with soil conditions. In an old-growth spruce-beech forest with high soil diversity we studied how the development of tree populations differs among different soils. Data from tree censuses carried out in 1972, 1996 and 2010 in the Boubin Primeval Forest in the Czech Republic were combined with detailed soil sampling to assess the relative abundance of beech and spruce and the role of the main drivers of population dynamics (tree growth, mortality and recruitment) in changes with respect to soils. The spatial distribution of populations of the two species primarily reflected a gradient of soil hydromorphism, with beech dominating drier soils and spruce dominating wetter soils. Over the 38 years, beech expanded on all major soils, yet the most important drivers differed. The only driver acting in favour of spruce on certain terrestrial soils was its faster radial growth. However, the effect was weaker than the effect of drivers that prioritized beech, mainly tree mortality. Fine-scale mortality (deaths of individual trees) was more significant on terrestrial soils, while the effect of coarse-scale mortality (deaths from a single severe windstorm event) increased towards hydromorphic soils. Certain soils (Histosols and Albic Podzols) diverged from the general trends because of their different disturbance regimes and specific tree–soil interactions. Soils play an important role in the dynamics of an old-growth spruce-beech forest. Their physical and chemical properties together with specific disturbance regimes determine fine-scale differences in tree species composition. At the same time, soils themselves are affected by trees, e.g. through acidification. The current expansion of beech is expected to continue on terrestrial soils but will probably slow down with increasing soil wetness.

Biochar is one of the most widely used ameliorants for soil amendment, which is known as factor which rises crop yields and levels of soil biological activity. Nowadays, it is under investigated how biochar application affects the dynamics of the humic components and whole soil organic matter (SOM) and the processes of its alteration. This investigation is aimed to evaluate the influence of biochar on the content, composition, and transformation of humic acids (HAs) as the main component of the SOM. The incubation experiment was carried out on three Podzol Antric soils, with varying amounts of initial total organic carbon. The incubation time was 90 days, using biochar gravimetric doses of 0.1 and 1.0%. The biochar was produced by fast pyrolysis of birch and aspen wood at 550 °С. Humus composition was analyzed for the organic matter fractions extracted with 0.1 M NaOH (containing HAs 1 + fulvic acids (FAs) 1) and 0.1 M Na4P2O7 (containing HAs 1 + FAs 1 + HAs 2 + FAs 2). Isolated HAs were characterized for their elemental composition (C, N, H, and S) and molecular composition with the use of solid-state 13C nuclear magnetic resonance (13C-NMR) techniques. We found that 0.1% of biochar amendment does not influence SOM mineralization, but 1.0% of biochar increases the mineralization by 15–18%. This process is accompanied by changes in the composition and properties of the HS. The increased proportion of HA aromatic fragments in biochar indicates an increasing of their stability. However, in soils with high humus content and a significant amount of insoluble matter, the processes of mineralization and the growth of HAs are taking place simultaneously. The replenishment of HAs could be the outcome of both the intensification of the transformation processes (mineralization and humification) of the more sustainable insoluble matter compounds and the humification of the biochar itself. The influence of biochar on humification in Podzol Antric soils was revealed on the basis of incubation experiment. Both negative and positive changes under biochar in HS system were demonstrated. The active decrease of humus total contents and also the labile HS ought to qualify as negative changes. The increase of HA chemical maturity that leads to the stability of humus in whole as well as the intensive new HA formation thought to qualify as positive changes.

The main aim of the study was to examine the biochar efficiency in copper (Cu) ion removal from Haplic (Luvisol, Podzol) soils. In other words, the most effective biochar dose and the most favorable environment pH value were proposed. The copper removal was carried out based on the adsorption process. The results of kinetics measurements were modeled using Richie equation, whereas the adsorption isotherms using Langmuir–Freundlich and Dubinin–Radushkevich equations. The copper removal is a strongly pH-dependent process which is associated with variability of chemical Cu forms and various reactivities of organic molecules. The Cu adsorption amount was higher on silty Haplic Luvisol than on sandy Haplic Podzol mainly due to higher content of organic carbon, functional groups, clay and silt fractions as well as larger surface area. Moreover, the biochar addition increased linearly the soil surface charge and contributed to higher copper adsorption in the whole range of investigated ion concentrations. The higher the biochar dose added, the more Cu ions were adsorbed.

Little is known about the geochemical baseline of Antarctic soils in different environments. We investigated the soil geochemistry of the two main landscape units of Harmony Point (Nelson Island, Maritime Antarctica): the coastal domain and the upper platform. Fourteen soil samples (seven in each landscape unit) were divided according to depth (hA for surface and hC for subsurface horizons) and characterized by their major, trace elements and REE concentrations. The concentration of major elements (SiO2, TiO2, Al2O3, Fe2O3, MgO, CaO, MnO, and K2O) were determined by X-ray fluorescence, whereas trace elements were quantified by inductively coupled plasma-optical emission spectrometry (Co, Ni, As, Cd, Pb, Ba, Cr, Cu, V, Zn, and Zr) and REE by inductively coupled plasma mass spectrometry. The results showed geochemical variation with depth, either related to pedological processes (phosphatization, humification, podzolization, and cryoturbation), and parent material constitution (andesitic basalt in upper platform and mixed volcanic sediments in coastal domain). The main chemical aspects distinguishing Harmony Point soils from other Maritime Antarctic soils from the vicinity are: (i) higher CIA index; (ii) P2O5 enrichment due to bird guano and enhanced pedogenesis; (iii) REE retention; (iv) enrichment in Fe2O3 and S concentrations. The REE concentration was influenced by weathering processes combined with allochthonous inputs, such as volcanic ashes and iceberg-transported granitic boulders at the coastal domain. The Harmony Point soils are little subjected to anthropic impacts, so they can be used as a basis for environmental monitoring programs in the Maritime Antarctica region.

The application of carbon-rich substrates to agricultural soils is discussed as a strategy to improve soil properties and fertility, which can affect plant physiological traits and enhance agricultural crop yield. The aim of this study was to evaluate if shungite, carbon-rich sedimentary-volcanic rock, may improve plant ecophysiological traits under sufficient water supply as well as soil water deficit. A pot culture experiment was conducted with onion (Allium cepa L.) seedlings, using four shungite concentrations (0, 5, 10 and 20 g kg−1) in an Umbric Podzols and two water regimes: well-watered and drying-wetting cycles. Soil water deficit decreased root nutrient content, depressed seedlings growth, net CO2 assimilation rate (An), stomatal conductance (gs) and the respiration rates in both darkness (Rd) and the light (Rl), but increased water use efficiency (WUE) at leaf level. Shungite application decreased the leaf necrosis under both water regimes and increased total leaf length of DW seedlings. Compared with the well-watered conditions, under drying-wetting cycle shungite stimulated the increase of the An rate and WUE at low measurement temperature. No significant effect of shungite was found for Rd, Rl, Rl/Rd, Rd/Ag (Ag = An + Rl) and Rl/Ag regardless soil water regimes. Shungite application was not so successful to eliminate the negative effects of soil water deficit on growth and physiological processes of A. cepa. The observed positive effects of shungite on the physiological traits of onion seedlings were more likely associated with the increase in the content of nutrients than with the improvement in soil water properties.

The boreal forest is among the largest terrestrial biomes on earth, storing more carbon (C) than the atmosphere. Due to rapid climatic warming and enhanced human development, the boreal region may have begun transitioning from a net C sink to a net source. This raises serious concern that old biogenic soil C can be re-introduced into the modern C cycle in near future. Combining bio-decay experiments, mixing models and the Keeling plot method, we discovered a distinct old pre-bomb organic carbon fraction with high biodegradation rate. In total, 34 ± 12% of water-extractable organic carbon (WEOC) in podzols, one of the dominating boreal soil types, consisted of aged (~ 1000 year) labile C. The omission of this aged (i.e., Δ14C depleted) WEOC fraction in earlier studies is due to the co-occurrence with Δ14C enriched modern C formed following 1950s nuclear bomb testing masking its existence. High lability of aged soil WEOC and masking effects of modern Δ14C enriched C suggests that the risk for mobilization and re-introduction of this ancient C pool into the modern C cycle has gone undetected. Our findings have important implications for earth systems models in terms of climate-carbon feedbacks and the future C balance of the boreal forest.

Wood ash is alkaline and contains base-cations. Application of wood ash to forests therefore counteracts soil acidification and recycle nutrients removed during harvest. Wood ash application to soil leads to strong vertical gradients in physicochemical parameters. Consequently, we designed an experimental system where small-scale vertical changes in soil properties and prokaryotic community structure could be followed after wood ash application. A mixed fly and bottom ash was applied in dosages of 3 and 9 t ha−1 to the surface of soil mesocosms, simulating a typical coniferous podzol. Soil pH, exchangeable cations and 16S prokaryotic community was subsequently assessed at small depth intervals to 5 cm depth at regular intervals for one year. Wood ash significantly changed the prokaryotic community in the top of the soil column. Also, the largest increases in pH and concentrations of exchangeable cations was found here. The relative abundance of prokaryotic groups directionally changed, suggesting that wood ash favors copiotrophic prokaryotes at the expense of oligotrophic and acidophilic taxa. The effect of wood ash were negligible both in terms of pH- and biological changes in lower soil layers. Consequently, by micro-vertical profiling we showed that wood ash causes a steep gradient of abiotic factors driving biotic changes but only in the top-most soil layers.

Background We applied Fourier-Transformed Infrared Spectroscopy (FTIR) techniques in combination with selective humus extractions to investigate in situ the chemical features of organic matter in three soil profiles recently developed from Dutch sand dunes, under well-documented vegetation sequence and containing a relatively simple mineral-organic matter system. Water-soluble and alkaline-soluble extracts were also studied to match the changes of humus in the soil residues. Results Diffuse Reflectance Infrared Fourier Transform (DRIFT) and transmission spectra differed in resolution and sensitivity. DRIFT was superior in revealing structural information on the organic matter present in the soil samples whereas transmission spectra showed higher resolution for the bands of inorganic material at lower spectral frequencies. Differences between H and B horizons were due to the amount of hydrophilic organic acids, partly unsaturated, that were extracted by alkali. Extractable carboxylic acids and other hydrophilic compounds such as peptides and carbohydrates were larger in the less developed soils under pine and crowberry than in the more advanced profiles under beech. Humin residues from both H and B horizons retained unextractable aliphatic components and carboxylic groups involved in strong complexes with minerals, thereby confirming other findings that showed the largely aliphatic character of the unextractable humic fraction. Accumulation of poorly-soluble organic materials in these soils occur by protection from biodegradation due both to complexation with soil minerals and to a process by which apolar humic constituents form a separate hydrophobic phase where no biological activity can take place. Transport of poorly soluble compounds from H to B horizons, noticed especially in the more developed profiles, may have occurred through humic aggregates containing hydrophobic phases. Conclusions This work shows that the DRIFT technique in combination with soil chemical treatments can be suitably employed to investigate the changes of organic matter in whole soil samples and represents a valid tool to investigate the role of organic matter in soil profile development.

Methanotrophy of arable soils is affected by N fertilization, but the knowledge about the effect of oxygen level is poorly understood; soil aeration can fluctuate and zones of low oxygen are widespread in soil. We monitored CH4 oxidation in three mineral soils (Eutric Cambisol, Haplic Podzol, Mollic Gleysol) under laboratory conditions by varying the O2 level (from 20 to 2% O2), with or without NH4+ (100 mg N kg−1). In controls (without NH4+), CH4 was oxidized completely in the O2 range from oxia (20% O2) to high hypoxia (5% O2), while the process was inhibited under microoxia (2% O2). Ammonium application decreased CH4 consumption in all soils. This negative effect was stronger at 20% and 2% O2 than under hypoxia. The highest CH4 oxidation rates and the shortest initial (lag) phases in both control and NH4+-amended soils were observed under high (5% O2) and low (10% O2) hypoxia.

Global and local climate changes could disturb carbon sequestration and carbon stocks in forest soils. Thus, it is important to characterize the stability of soil organic matter and the dynamics of soil organic carbon (SOC) fractions in forest ecosystems. This study had two aims: (1) to evaluate the effects of altitude and vegetation on the content of labile and stabile forms of organic carbon in the mountain soils; and (2) to assess the impact of the properties of soil organic matter on the SOC pools under changing environmental conditions. The studies were conducted in the Karkonosze Mountains (SW Poland, Central Europe). The content of the most labile fraction of carbon (dissolved organic carbon, DOC) decreases with altitude, but the content of fulvic acids (FA), clearly increases in the zone above 1000 m asl, while the stabile fraction (humins, non-hydrolyzing carbon) significantly decreases. A higher contribution of stabile forms was found in soils under coniferous forests (Norway spruce), while a smaller - under deciduous forests (European beech) and on grasslands. The expected climate change and the ongoing land use transformations in the zone above 1000 m asl may lead to a substantial increase in the stable humus fraction (mainly of a non-hydrolyzing carbon) and an increase in the SOC pools, even if humus acids are characterized by a lower maturity and greater mobility favorable to soil podzolization. In the lower zone (below 1000 m asl), a decrease in the most stable humus forms can be expected, accompanied by an increase of DOC contribution, which will result in a reduction in SOC pools. Overall, the expected prevailing (spatial) effect is a decreasing contribution of the most stable humus fractions, which will be associated with a reduction in the SOC pools in medium-high mountains of temperate zone of Central Europe.

Heavy metal contamination is a priority issue affecting millions of hectares of soil throughout the world. One of the most promising, environmentally friendly, and cost-effective approaches to restore polluted soils could be applying organic amendments. We investigated the remediation potential of three types of humic products with regard to their effect on the bioavailability of Pb and Zn, content of nutrients, and the ability to mitigate acute phytotoxicity in contaminated soil. Spodosol samples were spiked with Pb (550 mg kg−1) and Zn (880 mg kg−1). Then, two different commercial humic products (from peat and lignosulfonate) and natural humic acids (from brown oxidized coal) were added in two doses to reach an equal content of carbon: a 10% increment and a 30% increment of the initial total organic carbon in the soil. After 30 days, the content of metals and nutrients (S, K, Na, Ca, Mn, P) was determined by the sequential extraction (i−H2O, ii−NH4COOH pH 4.8, iii–CH3COOH). The effect of humic products on heavy metals bioavailability was evaluated using the calculated partition indexes. Seed germination and root elongation of Sinapis alba were also determined. Chemical and biochemical variables were aggregated by the principal component analysis. Humic products reduced the amount of bioavailable fractions of Pb and Zn in soils. The partition index, which quantitatively describes bioavailable fractions of the Zn and Pb in the soil, was 28–49% lower than in the spiked (Pb+Zn) control. The inhibition of root elongation and seed germination of mustard by Zn and Pb was significantly mitigated by humic products; in the soil test, the root length and seed germination were up to 36–87% higher than those of the Pb+Zn control and did not differ from those in the non-amended treatments. This effect may have been associated with the structural differences (H/C and O/C ratio) and content of nutrients (Na and K) in humic products. Commercial humic products used in poor multi-contaminated soils can maintain plant growth by improving nutrient status due to heavy metals immobilization and can be a promising approach to remediate the soil contaminated with heavy metals at extremely high concentrations.

The poor adsorption capacity of sandy soils is one of the primary reasons of a high level of phosphorus (P) leaching. Silicon (Si)-rich soil amendments have the potential to improve the low absorption capacity of sandy soils for P. The objective of this study was to evaluate the ability of different Si-rich materials to regulate P adsorption and retention by sandy soils. Amorphous fine silica (FSS), calcium silicate (CaSiO3), chemically pure CaCO3, and two types of Ca-silicate slags from metal industry (Pro-Sil) and chemical industry (TS) were used in laboratory experiments being conducted with pure quartz sand and cultivated and virgin Entisols and Spodosols collected in the South Florida. The binding energy-related constants were evaluated for soils treated by Si-rich materials and then incubated during 2 months. The following row of tested materials on the increasing level of “affinity parameter” was determined: for virgin Spodosol, Pro-Sil < CaCO3 < FSS< CaSiO3 < TS; for cultivated Spodosol, FSS < Pro-Sil < CaCO3< CaSiO3 < TS; for virgin Entisol, Pro-Sil < CaSiO3 < CaCO3 < FSS < TS; and for cultivated Entisol, FSS < Pro-Sil < CaSiO3 < CaCO3 < TS. Chemical, physical, and physical-chemical mechanisms of increasing soil adsorption capacity are hypothesized and discussed to explain the results obtained. The conducted experiments have demonstrated high prospective of Si-rich materials for reduction of P leaching from cultivated sandy soils.

Here, we aimed to assess the contamination of Podzol soils in a subalpine zone of the Karkonosze Mountains. Cu, Pb, and Zn concentrations in the soil and the patterns of their speciation are discussed in relation to the possible influence of airborne industrial emissions and the stage of degradation of dwarf mountain pine stands. The study was conducted in the Karkonosze, a mountain range in the Sudetes, on the boundary between Poland and the Czech Republic. We examined Podzols derived from granites under dwarf mountain pine stands at two stages of degradation (without visible degradation vs. dead). These two sites were 100 m apart, at an altitude of 1400 m above sea level (upper mountain forest zone). Soil samples were collected from all distinguished soil horizons and their basic soil properties and heavy metal (Cu, Pb, and Zn) concentrations (and their speciation) determined by sequential extraction according to the method of Zeien and Brummer. The Cu concentrations in these soils were relatively low, typical for soils derived from granite and did not differ considerably within soil profiles. The residual Cu fraction was a predominant one in all mineral horizons. The Pb concentrations in the surface organic horizons were clearly higher than those in similar horizons of European lowland forest soils. This distribution of Pb in the mineral horizons was apparently associated with soil colloid distribution that developed in the process of podzolization, indicating the minimum concentrations in eluvial E horizons and enhanced concentrations in illuvial Bh horizons. The organically bound fraction made up about 40% of total Pb in the Bh horizons. Zn concentrations were highest in the deepest parts of the soil, where the predominant fraction was residual, while relatively high amounts of easily mobilizable Zn were present in ectohumus. Very high concentrations of Pb in ectohumus have most likely been caused by a long-distance transport of anthropogenic emissions. The concentrations of Pb or other metals found in soils cannot be considered to have been the principal causes of the ecological disaster observed in the Karkonosze Mountains. The highest concentrations of Pb in ectohumus, as well as its high contributions in the organically bound fraction, confirm a crucial role of organic matter in Pb accumulation in soils.

Rumex confertus is known to be one of the most serious invasive weed species infesting meadows, pastures and ruderal lands throughout the Central Europe. Rumex confertus was grown in pot experiments using 8 soil types at 5 concentrations of nitrogen (N) and phosphorus (P). Based on harvest data, the variables, seedlings emergence, root: shoot (R: S) ratio, N and P concentration, chlorophyll content, Relative Colimitation Index (RCI) and dry matter allocation to plant components, were determined. N and P addition stimulated the growth of plants in different soils, as reflected by a significant increase in seedling growth parameters such as total plant biomass and shoot biomass. Across all soil types, emergence of seedlings was negatively affected by very high N, but positively affected by increased P availability. This study indicates that Dystric Arenosol, Entic Podzol, Brunic Arenosol and Calcaric Leptosol are unfavorable for R. confertus growth, excluding R. confertus completely. Moreover, evidence suggests that plant growth is limited by both N and P, therefore R. confertus could be controlled by reducing available N and P content in the soil.

Understanding the effects of elevation and related factors (climate, vegetation) on the physical and chemical soil properties can help to predict changes in response to future climate or afforestation forcings. This work aims to contribute to the knowledge of soil evolution and the classification of forest soils in relation to elevation in the montane stage, with special attention to podzolization and humus forms. The northern flank of the Moncayo Massif (Iberian Range, SW Europe) provides a unique opportunity to study a forest soils catena within a consistent quartzitic parent material over a relatively steep elevation gradient. With increasing elevation, pH, base saturation, exchangeable potassium, and fine silt-sized particles decrease significantly, while organic matter, the C/N ratio, soil aggregate stability, water repellency and coarse sand-sized particles increase significantly. The soil profiles shared a set of properties in all horizons: loamy-skeletal particle-size, extreme acidity (pH-H2O

The impacts of fly ash on the chemistry of forest floors were previously described in literature, while impacts on soil properties were less recognised. Soil investigations were focussed mainly on increases of pH and base saturations in surface horizons. The purpose of this study was to describe the influence of alkaline fly ash blown out from the dumping site of a lignite-fired power plant on pH changes of ectohumus horizons of Podzols and the morphology of deeper horizons. We investigated the soil profiles of Podzols derived from loose quartz sand and developed under pine forest surrounding the dumping site of the power plant Belchatow, central Poland. In the vicinity of the fly ash dumping site, five Podzol profiles located at a distance of 50 m from the dumping site were investigated, as well as soil profiles located along the transect set at distances of 50, 300, 800 and 2000 m from the dumping site. Control profiles were located at a distance of 7.3 km from the dumping site. Soil morphology was described in the field and the following properties were determined: soil texture, hydrolytic acidity, exchangeable cations, total organic carbon and total nitrogen content. The pH values of Podzol ectohumus horizons located close to the dumping site ranged from 6.01 to 7.34 compared to a range of 3.08–3.72 in the control. Ectohumus horizon located 300 m from the dumping site showed a pH range of 4.13–4.26, while at a distance of 800 m, the pH values did not differ from those of the control site. The upper part of the eluvial soil horizons located close to the dumping site had been transformed into transitional AE horizons in which humic substances translocated from ectohumus horizons were accumulated. Moreover, the organic carbon content of this horizon increased compared to the carbon content of the illuvial Bs horizon located below it. Under the influence of alkalisation of upper horizons, the illuvial Bhs horizons vanished and were transformed into Bs horizons. Changes in soils affected by fly ashes are connected with alkalinisation of ectohumus horizons. Podzolisation processes can be reduced or even completely stopped regarding the distance from the dumping site. Eluvial Podzol horizons located close to the dumping site may be transformed into AE horizons in which humic substances translocated from ectohumus horizons are accumulated. Due to transformation and translocation of organic components, Bhs horizons can be transformed into Bs horizons.

The study of hard rock conversion into fine earths and clayey materials in the pedosphere is important in understanding the relative proportions of recent soil features to features that were inherited from ancient epochs. Cold environments are widely thought to be areas of physical weathering, but the coexistence of physical and chemical processes have also been shown. To further examine mafic rock (dolerite) weathering in soil environments and the conversion into clayey materials, Entic Podzols formed in the cold continental climate were studied. The key study was located in the central part of the flood basalt complex, or traps (traprocks), of the Central Siberian Plateau (Russia). The qualitative mineralogy was studied using X-ray diffraction and the quantitative mineral composition was determined using X-ray diffraction and subsequent Rietveld analysis. The micromorphological characteristics of the soils were studied in thin sections. Dolerite fragments and fine earths were sampled from soil profiles underlain by dolerite. XRD analyses indicated that pyroxene and especially plagioclase contents in the dolerite fragments and fine earths decreased from the bottom to the top soil horizons mostly in the mature soil profiles that were affected by chemical weathering of dolerite. The dioctahedral and trioctahedral smectites in the soils were inherited from a dolerite previously subjected to chemical weathering. The smectite was conserved in the inherited aggregates and protected against dissolution even in acidic soil horizons. Recent pedogenesis processes fractured individual fragments, converted it into soil micromass, and slightly decreased the total smectite content of the

Drying-rewetting and freezing-thawing can drastically alter P availability in soil. We studied how these weather events affect microbial immobilisation/mobilisation of P on the four soil types from a climatic gradient with increasing annual mean temperatures and a progressive decrease in precipitation: Podzol, Phaeozem, Chernozem and Kastanozem. Soils were exposed to (1) optimal moisture and temperature, (2) drying-rewetting and (3) freezing-thawing. Soils were treated with a 33P spike immediately after rewetting or thawing to simulate P pulse. Thereafter, P immobilisation by soil microorganisms was estimated by direct fumigation and anion exchange membrane techniques. To ensure correct estimation of microbial P (Pmic), the conversion factors kP were determined individually for each soil by 33P labelling with the correction for 33P sorption and 31P–33P isotopic exchange. The membrane extraction minimised both sorption and isotopic exchange of P released with both sorption and isotopic exchange coefficients close to 0.9 irrespectively of the soil. Specific kP varied from 0.19 to 0.38. Pmic values followed the pattern freezing-thawing < drying-rewetting < optimal conditions, varying from 2.0 to 36.6 mg P kg−1. Intensive microbial immobilisation of 33P after rewetting (up to 41 %) demonstrated a conversion of dissolved P to Pmic potentially available for plant nutrition. Remarkably, no detectable microbial immobilisation of 33P was found in the freezing-thawing treatment. In contrast to drying, freezing decreased total Pmic by up to 7.5 times. Values of membrane-extractable 33P increased in the order drying-rewetting < control < freezing-thawing, and up to 77 % of added 33P was recovered in dissolved P forms after thawing, indicating the potential risk of P leaching after freezing-thawing events.

The contamination of soil with petroleum products is a major environmental problem. Petroleum products are common soil contaminants as a result of human activities, and they are causing substantial changes in the biological (particularly microbiological) processes, chemical composition, structure and physical properties of soil. The main objective of this study was to assess the impact of soil moisture on CO2 efflux from diesel-contaminated albic podzol soils. Two contamination treatments (3000 and 9000 mg of diesel oil per kg of soil) were prepared for four horizons from two forest study sites with different initial levels of soil water repellency. CO2 emissions were measured using a portable infrared gas analyser (LCpro+, ADC BioScientific, UK) while the soil samples were drying under laboratory conditions (from saturation to air-dry). The assessment of soil water repellency was performed using the water drop penetration time test. An analysis of variance (ANVOA) was conducted for the CO2 efflux data. The obtained results show that CO2 efflux from diesel-contaminated soils is higher than efflux from uncontaminated soils. The initially water-repellent soils were found to have a bigger CO2 efflux. The non-linear relationship between soil moisture content and CO2 efflux only existed for the upper soil horizons, while for deeper soil horizons, the efflux is practically independent of soil moisture content. The contamination of soil by diesel leads to increased soil water repellency.

Fluvial export of organic matter from the terrestrial catchment to the aquatic system is a large and increasing carbon flux. The successful reduction in sulfuric acid deposition since the 1980s has been shown to enhance the mobility of organic matter in the soil, with more terrestrially derived dissolved organic matter (DOM) reaching aquatic systems. Changes in soil acidity also affect the quality of the DOM. In this study we explore the consequences this may have on the reactivity and turnover of the terrestrially derived DOM as it reaches the aquatic system. DOM of different quality (estimated by absorbance, fluorescence and size exclusion chromatography) was produced through extraction of boreal forest O-horizon soils from podzol at two sulfuric acid concentrations corresponding to natural throughfall in spruce forest in Southern Sweden around 1980 and today. Extraction was done using two different methods, i.e. field leaching and laboratory extraction. The DOM extracts were used to assess if differences in acidity generate DOM of different reactivity. Three reactivity experiments were performed: photodegradation by UV exposure, biodegradation by bacteria, and biodegradation after UV exposure. Reactivity was assessed by measuring loss of dissolved organic carbon and absorbance, change in fluorescence and molecular weight, and bacterial production. DOM extracted at lower sulfuric acid concentration was more susceptible to photooxidation, and less susceptible to bacterial degradation, than DOM extracted at a higher sulfuric acid concentration. Thus the relative importance of these two turnover processes may be altered with changes in acid deposition.

Borneo’s tropical heath (kerangas) forest has limited soil nutrient availability, and high variation in aboveground structure and fine-root biomass. This variation depends on altitude and soil nitrogen availability. To elucidate the biotic and abiotic factors affecting the variation in fine-root biomass (FRB

Soil microbial biomass is a key source of soil organic carbon (SOC), and the increasing propor- tion of microbially derived SOC is thought to drive the enrichment of 13 C during SOC decomposition. Yet, little is known about how the d 13 C of soil microbial biomass differs across space or time, or with the composition of the microbial community. Variation in soil microbial d 13 C may occur due to variation in substrates used by soil microorganisms, and variation in how different microorganisms synthesize biomass. Understanding these variations in soil microbial d 13 C would enable more accurate interpretation of patterns in the d 13 C of SOC. Here, we report the variation in d 13 C values of individual phospholipid fatty acids

The magnitude of the carbon flux between soil and atmosphere has prompted efforts to better understand the controls over the fate of carbon in plant litter that re-enters the atmosphere as carbon dioxide or is sequestered as soil organic carbon (SOC). It remains unresolved if the long-term fate of litter carbon is driven by biochemical properties of litter or by soil properties that reduce the ability of soil organisms to decompose litter-derived carbon. The prominent role that reactive soil minerals play in stabilising SOC have hindered investigation into the single role of litter quality on long-term SOC stability. Here we investigated the independent effects of litter quality on soil carbon stabilisation across a 460,000 year sand dune chronosequence characterised by a pronounced nutrient and litter quality gradient with minimum presence of interfering soil minerals. Using a steady state turnover model to interpret radiocarbon activity in soils collected ≈40 years apart, we show that the turnover time of SOC in the A horizon averaged 22 years (ranging from 16 to 27 years) across the chronosequence. This finding strongly contrasts other chronosequences where SOC turnover rates range from 60 to 726 years in concert with changing abundance and composition of soil minerals. Our study demonstrates that the long-term stability of SOC in surface horizons may be largely determined by interaction with soil minerals and that litter quality per se does not govern carbon stabilisation.

Background and aims Soil evolution in mountain areas is strongly influenced by vegetation and terrain topography. In managed forests, however, relationships of the soil to the environment are modified or masked by human intervention. The objective of our study was to uncover the mutual effects of topographic and forest stand factors on the evolution and variability of soils in natural mountain spruce forests.

Soil organic matter (SOM) in boreal forest ecosystems can be strongly transformed by fires which, in turn, can affect soil physical and biological properties such as water repellency and nutrient cycling. The article contains the results of a study on SOM content in fire-affected lichen pine forests of the middle taiga subzone of the European part of Russia (Komi Republic). Soils which survived surface fires 2, 10, 16 years ago and unburned area were studied. We investigated changes in SOM composition using 13C NMR spectroscopy, and we measured water-soluble organic carbon (WSOC) content, polycyclic aromatic hydrocarbons (PAHs) concentrations, and contact angles of water droplets on soils. Forest fires increased pyrogenic organic carbon content and also largely transformed SOM composition. 13C NMR spectroscopy showed that the SOM composition of densimetric fractions in pyrogenic and unburned soil greatly differs. Fires increased the aromatic content in SOM composition of light fractions. The highest amount of aromatic carbon probably pyrogenic origin accumulated in fractions of free and occluded organic matter. According to 13C NMR spectroscopy, the aromatic component of organic matter increased in the pyrogenic horizons. The strongest PAHs concentrations occurred in the fractions of free particulate and occluded organic matter, in reference and fire-affected soils. The presence of PAHs in light densimetric fractions may serve as markers of past fire and fire intensity. In the initial years after fire, there was a decrease in the content of WSOC compounds; however, the WSOC content recovered with the recovery of ground vegetation. Our results showed that the greatest changes of contact angles were in upper pyrogenic soil horizons, whereas fires did not modify the contact angle value of lower mineral horizons.

Soil development follows a predictable pattern of nutrient availability over hundreds to thousands of years, which drives changes in the composition and productivity of associated plant communities. However, our understanding of the influence of soil forming factors such as parent material on ecosystem development is constrained by the scarcity of appropriate chronosequences. We studied a chronosequence of coastal beach ridges at the mouth of the Arawhata River in Westland, New Zealand. The Arawhata chronosequence is formed of coarse gravel, so comparison with the nearby Haast chronosequence, formed of sand of the same lithological origin, presents a rare opportunity to isolate the influence of the physical nature of the parent material on ecosystem development. Soils at Arawhata are Entisols with a shallow organic horizon over unconsolidated rounded coarse gravel, although old soils demonstrate features of podsolization and are morphologically similar to Spodosols. The fine earth fraction is a small proportion of the total volume, but increased in surface mineral soils from 5% to 20% over approximately 2000 years of pedogenesis. Corresponding soil phosphorus concentrations in the fine-earth fraction declined markedly, from >900 mg P kg−1 in young soils to 135 mg P kg−1 in older soils. However, on a profile basis the fine-earth fraction at Arawhata contained little phosphorus (10 g P m−2 on a 300-year-old soil) compared to the same-aged soil at Haast (253 g P m−2). Total nitrogen concentrations declined in surface mineral soil but not in the organic horizon, so nitrogen to phosphorus ratios increased with pedogenesis only in the organic horizon. Tree basal area at Arawhata was lower than on similar-aged soils at Haast, and the tree community on the youngest undisturbed ridge at Arawhata included Nothofagus menziesii, an ectomycorrhizal species that appears only on old infertile soils at Haast. Similarly, tree ferns were rare on the youngest soil at Arawhata and became more abundant along the chronosequence, yet at Haast they were most abundant on the phosphorus-rich young soils and decreased with soil age. Collectively, these results suggest that ecosystem development along the Arawhata chronosequence represents ‘backward succession’, because phosphorus stocks in the fine earth increase during the early stages of pedogenesis, even as mass-based concentrations decline. We conclude that the nature of the parent material plays a key role in determining the basal area and composition of tree communities during succession in the region, although further studies are required to isolate the relative importance of chemical and physical characteristics of the substrate.

Soil characteristics regulate various belowground microbial processes including methanogenesis and, consequently, affect the structure and function of methanogenic archaeal communities due to change in soil type which in turn influences the CH4 production potential of soils. Thus, five different soil orders (Alfisol, Entisol, Inceptisol, Podzol and Vertisol) were studied to assess their CH4 production potential and also the methanogenic archaeal community structure in dryland irrigated Indian paddy soils. Soil incubation experiments revealed CH4 production to range from 178.4 to 431.2 μg CH4 g-1 dws in all soil orders as: Vertisol

Long-term trends in ion concentrations of bulk precipitation, throughfall, forest floor leachate (humus water) and shallow and deep soil water were assessed at two Sitka spruce (Picea sitchensis) stands—one on an Atlantic peat bog in the west of Ireland (Cloosh), the other on the east coast on a peaty podzol (Roundwood). Deposition at Cloosh was dominated by marine ions (sodium, [Na+], chloride [Cl−], and magnesium [Mg2+]), whereas bulk precipitation and throughfall at Roundwood was characterized by inputs of non-marine sulphate (nmSO4 2−), acidity and inorganic nitrogen (NH4 +, NO3 −). Significant declines in concentrations of nmSO4 2− and acidity in bulk precipitation and throughfall were observed at both sites. The decline in throughfall nmSO4 2− was significantly related to reductions in European sulphur dioxide (SO2) emissions. At Roundwood, SO4 2− declined significantly in humus, shallow and deep soil water. In deep soil water this was accompanied by a long-term increase in pH and a reduction in total aluminum (Altot). The recovery from acidification was delayed by high concentrations of NO3 −, which strongly influenced acidity and Altot concentrations. At Cloosh, there was a significant decline in SO4 2− in humus water but long-term trends were not evident in shallow or deep soil water; SO4 2− concentrations at these depths fluctuated in response to drought-events. Marine ions strongly influenced soil water chemistry at both sites; at Cloosh soil water acidity was strongly related to Na+ and Cl−, while at Roundwood, Na+, Cl− and Mg2+ influenced Altot concentrations. Dissolved organic carbon increased significantly in humus and soil water at Roundwood, where it was associated with declining acidity. Soil water at both sites was influenced by a combination of anthropogenic sulphur (S) and nitrogen (N) deposition, drought and sea-salt events. The study highlights the value of long-term monitoring in assessing the response of forest soils to S and N deposition against a background of climate influences on soil water through drought and sea-salt events.

Soil phosphorus (P) composition changes with ecosystem development, leading to changes in P bioavailability and ecosystem properties. Little is known, however, about how soil P transformations proceed with ecosystem development in boreal regions. We used 1-dimensional 31P and 2-dimensional 1H, 31P correlation nuclear magnetic resonance (NMR) spectroscopy to characterise soil organic P transformations in humus horizons across a 7,800 year-old chronosequence in Vasterbotten, northern Sweden. Total soil P concentration varied little along the chronosequence, but P compounds followed three trends. Firstly, the concentrations of DNA, 2-aminoethyl phosphonic acid, and polyphosphate, increased up to 1,200–2,700 years and then declined. Secondly, the abundances of α– and β—glycerophosphate, nucleotides, and pyrophosphate, were higher at the youngest site compared with all other sites. Lastly, concentrations of inositol hexakisphosphate fluctuated with site age. The largest changes in soil P composition tended to occur in young sites which also experience the largest shifts in plant community composition. The apparent lack of change in total soil P is consistent with the youth and nitrogen limited nature of the Vasterbotten chronosequence. Based on 2D NMR spectra, around 40 % of extractable soil organic P appeared to occur in live microbial cells. The observed trends in soil organic P may be related to shifts in plant community composition (and associated changes in soil microorganisms) along the studied chronosequence, but further studies are needed to confirm this.

The lead–zinc industry in the Bukowno region of southern Poland has polluted the surface layer of the surrounding soils mainly with lead (Pb), cadmium (Cd), zinc (Zn), arsenic (As), and thallium (Tl). Analysis of six soil profiles, taken on the east side of the postflotation waste site of the Mining and Metallurgical Plants ZGH "Bolesław" in Bukowno, showed that they were podzol soils, taking form of loose sands with neutral pH and reducing conditions. Concentration of organic matter in the horizons ranged from 2 to 80 %. The main components of the mineral soil were quartz, carbonates, K-feldspars, plagioclases, and micas (sericite). The highest total concentrations of metals were found in the O, A, and B horizons. Over 90 % of the Cd content, 80 % of the Pb content, 60 % of the Zn content, ∼60 % of the Tl content, and 20 % of the As content occurred as mobile forms. The corresponding total concentrations were 10 mg/kg Cd, 922 mg/kg Pb, 694 mg/kg Zn

Metal concentrations from stream waters in two geological blocks in Northern Ireland were compared to determine the contributions of catchment characteristics and in-stream conditions. One block is composed of metamorphosed schist and unconsolidated glacial drift with peat or peaty podzol (mainly humic) soils, while the other block consists of tertiary basalt with brown earth and gley soils. Water samples were collected from 52 stream sites and analysed for iron (Fe), manganese (Mn) and aluminium (Al) as well as a range of other chemical determinands known to affect metal solubility. Densities of metal-rich ochre deposit were determined for stream bed stone samples. Higher conductivities and concentrations of bicarbonate, alkalinity, calcium and magnesium occurred on basalt than on schist. Despite higher Fe and Mn oxide concentrations in basalt-derived non-humic soils, stream water concentrations were much lower and ochre deposit densities only one-third of those on schist overlain by humic soils. Neither rock nor soil type predicted Al concentrations, but pH and dissolved oxygen did. Peat-generated acidity and the limited acid neutralising capacity of base-poor metamorphosed schist have resulted in elevated concentrations of metals and ochre deposit in surface waters.

Soil chronosequences on marine terraces along the Pacific Coast of California and Oregon show evidence of podzolization, though soils ultimately evolve to Ultisols. It is not clear if this pathway of soil evolution can be extended to the humid, inland Oregon Coast Range. We analyzed soil properties for a fluvial terrace chronosequence sampled along the Siuslaw River (Oregon, USA) about 50 km from the Pacific coast. The seven terraces ranged in age from

Soil chronosequences provide an opportunity to examine the influence of long-term pedogenesis on the biomass and composition of associated tree communities. We assessed variation in the species composition of trees, saplings, and seedlings, and the basal area of adult trees, in lowland temperate rain forest along the Haast chronosequence on the west coast of the South Island of New Zealand. The sequence consists of Holocene dune ridges formed following periodic earthquake disturbance and is characterized by rapid podzol development, including a marked decline in phosphorus concentrations, accumulation of a thick organic horizon, and formation of a cemented iron pan. Tree basal area increased for the first few hundred years and then declined in parallel with the decline in total soil phosphorus, consistent with the concept of forest retrogression. There were also marked changes in the composition of the tree community, from dominance by conifers on young soils to a mixed conifer–angiosperm forest on old soils. Although a variety of factors could account for these changes, partial Mantel tests revealed strong correlations between tree community composition and soil nutrients. The relationships differed among life history stages, however, because the adult tree community composition was correlated strongly with nutrients in the mineral soil, whereas the seedling community composition was correlated with nutrients in the organic horizon, presumably reflecting differences in rooting depth. The changes in the tree community at Haast are consistent with disturbance-related succession in conifer–angiosperm forests in the region, but the opposite of patterns along the nearby Franz Josef post-glacial chronosequence, where conifers are most abundant on old soils. The Haast chronosequence is therefore an important additional example of forest retrogression linked to long-term soil phosphorus depletion, and provides evidence for the role of soil nutrients in determining the distribution of tree species during long-term succession in lowland temperate rain forests in New Zealand.

This paper reported the results of the determination of Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sr and Zn in Common Chanterelles (Cantharellus cibarius) Fr. and surface soil layer (0–10 cm) underneath the fruiting bodies. Mushrooms and soils were collected from a lowland site in the Hel Peninsula (Baltic Sea coast) and a high mountain site in the Tatra Mountains. The trace elements were determined using validated method and inductively coupled plasma — atomic emission spectroscopy (ICP-AES). Common Chanterelles that emerged at sites poor in mineral nutrients podzols of the Hel Peninsula forests efficiently bioconcentrated several essential trace elements (K, P, Co, Cu, Mn, Na, Zn), while the abundance of those elements in carpophores was around half less compared to specimens from Zakopane region and which emerged in soils much richer in minerals. Common Chanterelles collected at two spatially distant background areas in Poland were only weakly contaminated with metals such as Ag, Cd, Hg and Pb. The maximum tolerable Cd and Pb contents of certain cultivated mushrooms are regulated in the European Union by law and these hazardous metals in C. cibarius were far below tolerance limits set.

We measured spatial and temporal variations in carbon concentrations, isotopic compositions and exports during a complete hydrological cycle in nine watercourses draining a lowland forested podzolized catchment, flowing into the Arcachon lagoon (France). In addition, integrated fluxes of CO2 across the water-atmosphere interface were estimated to assess the relative importance of CO2 evasion versus lateral carbon transport at the catchment scale. Watercourse similarities and specificities linked to the local catchment characteristics are discussed and compared with other riverine systems. Low concentrations of suspended particulate matter and particulate organic carbon (POC) were generally measured in all the watercourses (8. 4 ± 3. 4 and 1. 6 ± 0. 6 mg L-1, respectively), reflecting limited mechanical soil erosion. The generally high POC content in the suspended matter (20 %), low Chl a concentrations (1. 3 ± 1. 4 μg L-1) and the relatively constant δ13C-POC value (near -28 ‰) throughout the year reveal this POC originates from terrestrial C3 plant and soil detritus. The presence of podzols leads to high levels of dissolved organic carbon (DOC; 6. 6 ± 2. 2 mg L-1). Similarly, high dissolved inorganic carbon (DIC) concentrations were measured in the Arcachon lagoon catchment (5. 9 ± 2. 2 mg L-1). The δ13C-DIC value around -20 ‰ throughout the year in many small watercourses reveals the predominance of terrestrial carbon mineralisation and silicate rock weathering in soils as the major DIC source. With pCO2 between 1,000 and 10,000 ppmv, all watercourses were a source of CO2 to the atmosphere, particularly during the low river stage. Organic carbon parameters remained relatively stable throughout the year, whereas DIC parameters showed strong seasonal contrasts closely linked to the hydrological regime and hyporheic flows. In total, the carbon export from the Arcachon watershed was estimated at 15,870 t C year-1 or 6 t C km-2 year-1, mostly exported to the lagoon as DOC (35 %), DIC (24 %) and lost as CO2 degassing to the atmosphere (34 %). © 2012 Springer Basel AG. ispartof: Aquatic Sciences vol:75 issue:2 pages:299-319 status: published

The availability of phosphorus (P) can limit net primary production (NPP) in tropical rainforests growing on highly weathered soils. Although it is well known that plant roots release organic acids to acquire P from P-deficient soils, the importance of organic acid exudation in P-limited tropical rainforests has rarely been verified. Study sites were located in two tropical montane rainforests (a P-deficient older soil and a P-rich younger soil) and a tropical lowland rainforest on Mt. Kinabalu, Borneo to analyze environmental control of organic acid exudation with respect to soil P availability, tree genus, and NPP. We quantified root exudation of oxalic, citric, and malic acids using in situ methods in which live fine roots were placed in syringes containing nutrient solution. Exudation rates of organic acids were greatest in the P-deficient soil in the tropical montane rainforest. The carbon (C) fluxes of organic acid exudation in the P-deficient soil (0.7 mol C m−2 month−1) represented 16.6% of the aboveground NPP, which was greater than those in the P-rich soil (3.1%) and in the lowland rainforest (4.7%), which exhibited higher NPP. The exudation rates of organic acids increased with increasing root surface area and tip number. A shift in vegetation composition toward dominance by tree species exhibiting a larger root surface area might contribute to the higher organic acid exudation observed in P-deficient soil. Our results quantitatively showed that tree roots can release greater quantities of organic acids in response to P deficiency in tropical rainforests.

In montane cloud forests (MCF), the main soil organic carbon (SOC) pool is believed to be constituted by organic debris accumulated on soil surface and, to a lesser extent, by the organic fraction associated with the mineral matrix. The vertical distribution of SOC within soil has strong implications on the composition, stabilization and turnover of the soil organic matter (SOM). In ecosystems like MCF, where the climatic and edaphic conditions varied with altitude, the SOM accumulation and stabilization mechanisms possibly respond to these changes. For that reason, we studied the vertical distribution, accumulation and chemical composition of SOM in five montane cloud forest communities located between 1,500 and 2,500 m a.s.l. Two main SOC accumulation patterns were found: one at 1,500, 1,950 and 2,400 m a.s.l., with SOC content gradually decreasing with depth (cumulative); and another at 2,050 and 2,500 m a.s.l. where SOC had a strong maximum in the surface horizon and a less pronounced increase the spodic horizon (eluviation–illuviation pattern). The total SOC pool in soil decreased in inverse relation to altitude from 227 C ha−1 at 1,500 m a.s.l. down to 143 mg C ha−1 at 2,500 m a.s.l. About 40–60 % of total SOC content corresponded to the surficial organic horizon. The chemical fractionation of the SOM denoted in general predominance of the fulvic acid fraction, and high content of humin and humic acid fractions. We considered that the main SOC vertical distribution processes were related to the raw humus accumulation, decomposition in situ, podzolization in the eluviation–illuviation pattern soils mainly.

Spodosols in Florida exhibit a unique hydrology including a fluctuating water table that can often reach the surface horizon during the summer months. This paper evaluated the effects of fluctuating water table on P fluxes and availability in a typical Florida Spodosol. The study was conducted on an established bahiagrass (Paspalum notatum Flugge) pasture grown on a Smyrna sand (sandy, siliceous, hyperthermic Aeric Alaquods). Phosphorus fluxes were measured using suction cup lysimeters installed at depths of 15, 30, 60, 90, and 150 cm. The 15- and 30-cm deep lysimeters were located above the spodic (Bh) horizon, whereas the remaining lysimeters (60-, 90- and 150-cm) were below the Bh horizon. A pressure transducer was installed at the center of the experimental site to monitor changes in water table depth. Two anion exchange membranes (2 × 6 cm) were buried in each plot at a 15-cm depth to estimate in situ P availability. During the 2-year study, leachate P concentrations in the lysimeters above the Bh horizon increased as water tables rose in the months of August and September. Conversely, P concentration measured in the lysimeters below the Bh horizon remained relatively constant (0.02 mg L−1). Soil P availability also increased (from 3.2 μg cm−2 in June to 9.2 μg cm−2 in August) in response to rising water table. Results showed that the fluctuating water table conditions experienced during the summer months in Florida cause upward flux of P from the Bh horizon, which increased soil P availability and susceptibility to off-site transport.

The sediment record from a 5.3-m core from Sargent Mountain Pond, Maine USA indicates strong co-evolutionary relationships among climate, vegetation, soil development, runoff chemistry, lake processes, diatom community, and water and sediment chemistry. Early post-glacial time (16,600–12,500 Cal Yr BP) was dominated by deposition of mineral-rich sediment, low in organic matter and secondary hydroxides of Al and Fe; pollen indicate tundra conditions; diatom taxa indicate pH between 7.5 and 8, and total P concentrations of about 25 μg L−1, favoring higher productivity. Chemical weathering was rapid, with high alkalinity, pH, Ca, and P in runoff. As climate ameliorated, about 12,500 Cal Yr BP, forest vegetation became established; soils would have developed vertical zonation, including organic matter accumulation, and incipient podzolic horizons, with accumulating secondary hydroxides of Al and Fe that sequestered P in the soils. Labile minerals (primarily apatite, Ca5(PO4)3(OH,F,Cl)) became depleted in the soil, further reducing the supply of P to the lake. Dissolved organic carbon (DOC) from soil organic matter mobilized Al and Fe to the lake where Al(OH)3 (primarily) and Fe(OH)3 (minor) were precipitated. The sedimenting hydroxides adsorbed P from the water column, further reducing bioavailable P. These long-term trends of moderating climate, and changing terrestrial biology, soils, and aquatic chemistry and phytoplankton were interrupted by the 1,000-year long Younger Dryas cooling, which led to a temporary reversal of these processes, a period that ended with the major onset of Holocene warming. The sequestration of P by soils would have strengthened because of long-term soil acidification and pedogenesis. The lake was transformed from a more productive, high P, high pH, low DOC system into an oligotrophic, relatively low P, acidic, humic lake over a period of 16,600 years, a natural trend that continues. In contrast to many human-affected lakes that become increasingly eutrophic, many lakes become more oligotrophic during their history. The precursors for that are: (1) absence of human land-use in watersheds, (2) bedrock lithology and soil with a paucity of soluble Ca-rich minerals, and (3) vegetation that promotes the accumulation of soil organic matter, podzolization, and increased export of metal-DOC complexes, particularly Al.

In order to understand the biological activity of humic substances (HS), the effect of four humic acids (HA) and one fulvic acid (FA) on seed germination and early growth of cosmopolitan weed Chenopodium album agg. were tested. Humic substances of diverse origin were used, namely purified commercial HA, HA isolated from lignite, cambisol and podzol, and FA from mountain spruce forest soil. Data processing by two-way ANOVA has shown that type of the tested substances was a more important factor on seed development than used concentration. The major differences in germination and length of shoots were found in the first days of the experiment. Commercial and lignite HA stimulated the seed germination and growth, while podzol HA inhibited them. After this initial phase, all humic substances stimulated the seed development, but these stimulations were not significant (P < 0.05). At the end of germination test, the greatest stimulation effect (up to 20%) was achieved with the lignite HA.

Soil variability was assessed in a 74.2-ha area within the Žofinský prales natural forest. Parameters evaluated for 1765 soil profiles inside 353 graticule plots were as follows: (1) thickness of organic horizons, (2) thickness and form of mineral horizons, (3) humus form (HF), (4) soil taxonomic unit (STU) and (5) anomalies. In addition, soil reaction (pHKCl) and oxidizable carbon content (Cox) were measured in the laboratory for 734 samples from the upper mineral (A) and lower mineral (B) horizons. The most frequently occurring humus form was mor followed by moder, hydromor and peaty T-horizon. Entic Podzols, Dystric Cambisols, Haplic Cambisols, Albic Podzols, Histic (or Haplic) Gleysols, Endogleyic Stagnosols, Fibric or Hemic or Sapric Histosols and Stagnic Gleysols were all present at the site despite its homogeneous geological bedrock. Overall coefficient of variance (CV) was lower in terrestrial soils compared with (semi-)hydromorphic soils. Overall variance decreased in both soil groups with increasing depth, as did CV differences between the fine (up to 10 m) and the locality scales. The lowest CV values occurred for Cox and pHKCl. The CV values differed between STUs as well. Compared to lower horizons, variograms of upper horizons showed greater autocorrelation at the intermediate spatial scale (10–320 m)—ranging from 50 to 150 m. Semivariance values, however, reached 70–80% of sill already at a distance of 10 m. The most significant factor of variability at all studied spatial scales is presumably the soil disturbance regime, followed by terrain micro-topography and the effect of tree species.

Dissolved organic carbon (DOC) is an important component of the C cycle in forest ecosystems, but dynamics and origin of DOC in throughfall and soil solution are yet poorly understood. In a 2-year study, we analyzed the radiocarbon signature of DOC in throughfall and soil solution beneath the Oa horizon and at 90 cm depth in a Norway spruce forest on a Podzol soil. A two-pool mixing model revealed that throughfall DOC comprised mainly biogenic C, i.e. recently fixed C, from canopy leaching and possibly other sources. The contribution of fossil DOC from atmospheric deposition to throughfall DOC was on average 6% with maxima of 8–11% during the dormant season. In soil solution from the Oa horizon, DO14C signature was highly dynamic (range from −8‰ to +103‰), but not correlated with DOC concentration. Radiocarbon signatures suggest that DOC beneath the Oa horizon originated mainly from occluded and mineral associated organic matter fractions of the Oa horizon rather than from the Oi or Oe horizon. Relatively old C was released in the rewetting phase following a drought period in the late summer of 2006. In contrast, the DO14C signature indicated the release of younger C throughout the humid year 2007. In soil solutions from 90 cm depth, DO14C signatures were also highly dynamic (−127‰ to +3‰) despite constantly low DOC concentrations. Similar to the Oa horizon, the lowest DO14C signature at 90 cm depth was found after the rewetting phase in the late summer of 2006. Because of the variation in the DO14C signatures at this depth, we conclude that DOC was not equilibrated with the surrounding soil, but also originated from overlaying soil horizons. The dynamics of DO14C in throughfall and soil solution suggest that the sources of DOC are highly variable in time. Extended drought periods likely have a strong influence on release and translocation of DOC from relatively old and possibly stabilized soil organic matter fractions. Temporal variations as well as the input of fossil DOC needs to be considered when calibrating DOC models based on DO14C signatures.